MS250 Problem

[MplsDon]

My MS 250 is not running right. I put a bore scope through the spark plug hole and got the attached pictures. I assume those detents in the cylinder wall and piston by the exhaust port are not supposed to be there? Would that cause poor running? If so, what’s the best source for replacements? Thanks

 

[SteveSr]

Saw ate a foreign object or a piece or a bearing that is disintegrating. You need to tear it apart to see what happened.

 

[Country bumpkin]

Steve is right. Those are simple to tear apart. I usually get a used 025/250 cylinder & piston off eBay along with a set of Caber rings. Be sure you replace oil seals.

 

[MplsDon]

Thanks. I found some inexpensive cylinder/piston sets on Amazon. I assume they’d be ok. I don’t see any seals though if just replacing cylinder and piston. ??

 

[Tobystihl]

Looks like someone tried to remove the clutch using a screwdriver through the exhaust port to lock the engine!!!

 

[MplsDon]

Do you think that’s enough to adversely affect engine performance?

 

[TRTermite]

Do you think that’s enough to adversely affect engine performance?

IF not performance I would be concerned of how long of a life the saw will have.
When you pull the muffler be prepared to continue tearing your saw down.
I will side with TobyStihl with the screwdriver stop comment and will wager neither of us are guilty of this procedure.
I will say I have been Tempted more than once.
I think there are 2 kinds of seals available. One kind to replace seals without removing bottom of clam. Another kind for when you have the crank separated from cylinder. (I Prefer for my peace of mind)

 

[Tobystihl]

Do you think that’s enough to adversely affect engine performance?

Yes, it's Fubar'ed... New pot and piston is required, then you'll be good to go!

 

[rupedoggy]

Take it apart. Sand out any budges into the cylinder in the jug. New piston and GTG. Or maybe just new rings if the dink in the side of the piston is not to bad.